Eric,

Just exactly how does this "salt fog" test correspond to your possible
end use environments?

David A. Douthit
Manager
LoCan LLC

Eric CHRISTISON wrote:

>Ok, thanks for the info.
>
>No clear cut answers but I guess PCB finish doesn't make that much
>difference.
>
>Can anyone tell me if lead free solders perform better in corrosive
>environments?
>
>Thanks,
>
>Eric Christison Msc
>Mechanical Engineer
>Consumer & Micro Group - Imaging Division
>STMicroelectronics
>33 Pinkhill
>Edinburgh
>EH12 7BF
>UK
>
>Tel:     +44 (0) 131 336 6165
>Fax:    +44 (0) 131 336 6001
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
>Sent: Tuesday, May 04, 2004 3:48 PM
>To: [log in to unmask]
>Subject: Re: [TN] Corrosion resistance of Ni/Au plating
>
>
>Hi folks! Some additional data - we (e.g. the industry technoweinees) are
>much too quick to jump to the conclusion that we have a galvanic
>compatibility problem when using either immersion gold or immersion silver
>pwb finishes. Rockwell Collins published a paper at the 2003 IPC Fall
>meeting which demonstrated that the galvanic impact was secondary to a
>standard corrosion reaction in a salt fog test - i.e. our tin/lead test
>samples which were in a galvanically happy couple situation underwent
>healthy corrosion. The galvanic compatibility tables are very important and
>should not be ignored but they also can be misleading depending on the
>environment/configuration. Collins has a follow up immersion silver,
>immersion gold, immersion tin, and tin/lead galvanic corrosion study in
>progress and will report the results sometime in early 2005.
>
>Dave
>
>
>
>                      Vladimir Igoshev
>                      <[log in to unmask]        To:       [log in to unmask]
>                      >                        cc:
>                      Sent by: TechNet         Subject:  Re: [TN] Corrosion
>resistance of Ni/Au plating
>                      <[log in to unmask]>
>
>
>                      05/04/2004 09:19
>                      AM
>                      Please respond to
>                      "TechNet E-Mail
>                      Forum."; Please
>                      respond to
>                      Vladimir Igoshev
>
>
>
>
>
>
>
>Rudy,
>
>It's not supposed to be any Au layer left after re-flow. It desolves in
>solder.
>
>Vladimir
>Sent from my Blackberry Wireless
>Vladimir Igoshev, 519-888-7465 ext.5283
>
>
>-----Original Message-----
>From: Rudy Sedlak <[log in to unmask]>
>To: [log in to unmask] <[log in to unmask]>
>Sent: Tue May 04 10:05:27 2004
>Subject: Re: [TN] Corrosion resistance of Ni/Au plating
>
>Central to this issue is the question of whether the Gold was completely
>covered by the Tin/Lead solder.
>
>I suspect it was not, and if it was not, this would set up a galvanic cell,
>which would accelerate the attack on the Tin Lead dramatically.
>
>Rudy Sedlak
>RD Chemical Company
>
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